Erythrocytes of the frog: structure and functions

Blood is a liquid tissue that carries out essential functions. However, in different organisms, its elements differ in structure, which is reflected in their physiology. In our article, we will dwell in detail on the features of red blood cells and compare human and frog erythrocytes.

Variety of blood cells

Blood is formed by a liquid intercellular substance, called plasma, and shaped elements. These include leukocytes, erythrocytes and platelets. The first are colorless cells that do not have a permanent shape and move independently in the bloodstream. They are able to recognize and digest foreign particles for the body by phagocytosis, so they form the immune system. This is the ability of the body to resist various diseases. Leukocytes are very diverse, possess immunological memory and protect living organisms from the moment they are born.

Platelets also perform a protective function. They provide blood clotting. This process is based on an enzymatic reaction of the transformation of proteins with the formation of their insoluble form. As a result, a blood clot is formed, which is called a thrombus.

Features and functions of erythrocytes

Erythrocytes, or red blood cells, are structures containing respiratory enzymes. Their shape and internal contents in different animals can vary. However, there are a number of common features. On average, erythrocytes live up to 4 months, after which they are destroyed in the spleen and liver. The place of their formation is the red bone marrow. Erythrocytes are formed from universal stem cells. And in newborns hematopoietic tissue has all types of bones, and in adults only in flat ones.

In the animal organism, these cells perform a number of important functions. The main one is respiratory. Its realization is possible due to the presence of special pigments in the cytoplasm of erythrocytes. These substances also determine the color of the blood of animals. For example, in mollusks it can be lilac, and in polychaete worms - green. Erythrocytes of the frog's blood provide it with a pink color, while in humans it is bright red. Connecting in the lungs with oxygen, they carry it to every cell of the body, where they give it up and attach carbon dioxide. The latter comes in the opposite direction and exhales.

Erythrocytes also transport amino acids, carrying out a nutritional function. These cells are carriers of various enzymes that can influence the rate of chemical reactions. Antibodies are located on the surface of red blood cells. Thanks to these substances of protein nature, red blood cells connect and neutralize toxins, protecting the body from their pathogenic effects.

Evolution of red blood cells

Erythrocytes of frog blood are a vivid example of an intermediate result of evolutionary transformations. For the first time such cells appear in primitive animals, which include ribbon-like worms of nemerte, echinoderms and mollusks. At their most ancient representatives, hemoglobin was located directly in the blood plasma. With the development of the need for animals in oxygen increased. As a result, the amount of hemoglobin in the blood increased, which made the blood more viscous, and made breathing difficult. The emergence of this was the emergence of red blood cells. The first red blood cells were fairly large structures, most of which is occupied by the nucleus. Naturally, the content of the respiratory pigment at this structure is insignificant, because there simply is not enough room for it.

In the future, evolutionary metamorphosis developed in the direction of reducing the size of red blood cells, increasing the concentration and disappearance of the nucleus in them. At the moment, the biconcave form of red blood cells is most effective. Scientists have proven that hemoglobin is one of the most ancient pigments. It even occurs in the cells of primitive infusorians. In the modern organic world, hemoglobin has retained its dominant position, along with the existence of other respiratory pigments, since it carries the greatest amount of oxygen.

Oxygen capacity of blood

In arterial blood, only a certain amount of gases can be present simultaneously in the bound state. This indicator is called the oxygen capacity. It depends on a number of factors. First of all, this is the amount of hemoglobin. The red blood cells of the frog in this respect are much inferior to the red cells of human blood. They contain a small amount of respiratory pigment and their concentration is low. For comparison: hemoglobin of amphibians contained in 100 ml of their blood binds an oxygen volume equal to 11 ml, and in humans this figure reaches 25.

Factors that increase the ability of hemoglobin to attach oxygen include increased body temperature, the pH of the internal environment, and the concentration of intracellular organic phosphate.

Structure of red blood cells of a frog

Considering erythrocytes of a frog under a microscope, it is easy to see that these cells are eukaryotic. All of them have a large decorated core in the center. It occupies a large enough space in comparison with respiratory pigments. In this regard, the amount of oxygen that they are able to tolerate is significantly reduced.

Comparison of human and frog erythrocytes

Red blood cells of humans and amphibians have a number of significant differences. They have a significant effect on the performance of functions. Thus, human erythrocytes have no nucleus, which significantly increases the concentration of respiratory pigments and the amount of oxygen transferred. Inside them is a special substance - hemoglobin. It consists of a protein and an iron-containing part - heme. Frog red cells also contain this respiratory pigment, but in a much smaller amount. The efficiency of gas exchange also increases due to the biconcave form of human erythrocytes. They are sufficiently small, so their concentration is greater. The main similarity of human and frog erythrocytes is the realization of a single function - respiratory.

Size of erythrocytes

The structure of erythrocytes of the frog is characterized by fairly large dimensions, which reach up to 23 μm in diameter. In humans, this indicator is much smaller. Its erythrocytes have a size of 7-8 microns.

Concentration

Due to their large size, the red blood cells of frogs are characterized by low concentration. So, in 1 cubic mm of blood of amphibians they are 0.38 million. For comparison, in humans this amount reaches 5 million, which increases the respiratory capacity of its blood.

Form of erythrocyte

Considering the erythrocytes of a frog under a microscope, you can clearly identify their rounded shape. It is less advantageous than doubly-concave discs of red blood cells of a human being, since it does not promote an increase in the respiratory surface and occupies a large volume in the bloodstream. The correct oval shape of the erythrocyte of the frog completely repeats that of the nucleus. It contains chromatic threads containing genetic information.

Cold-blooded animals

The shape of the frog's erythrocyte, like its internal structure, allows only a limited amount of oxygen to be transferred. This is due to the fact that amphibians do not need as much of this gas as mammals. It is very easy to explain this. Amphibians breathe not only through the lungs, but also through the skin.

This group of animals is cold-blooded. This means that the temperature of their body depends on the change in this index in the environment. This sign directly depends on the structure of their circulatory system. Thus, there is no septum between the chambers of the amphibian heart. Therefore, in their right atrium, venous and arterial blood is mixed and in this form goes to tissues and organs. Along with the structural features of red blood cells, this makes their gas exchange system not as perfect as in warm-blooded animals.

Warm-blooded animals

In warm-blooded organisms, body temperature is constant. These include birds and mammals, including humans. In their body, there is no mixing of venous and arterial blood. This is the result of having a complete septum between the chambers of their heart. As a result, all tissues and organs, except lungs, receive pure arterial blood, saturated with oxygen. Along with more perfect thermoregulation, this is facilitated by an increase in the intensity of gas exchange.

So, in our article we have examined what features red blood cells of a human and a frog have. Their main differences relate to the size, the presence of the nucleus and the level of concentration in the blood. Erythrocytes of frogs are eukaryotic cells, have larger dimensions, and their concentration is low. Because of this structure, they contain a smaller amount of respiratory pigment, so pulmonary gas exchange in amphibians is less effective. This is compensated by an additional system of cutaneous respiration. The features of the structure of red blood cells, the circulatory system and the mechanisms of thermoregulation determine the cold-bloodedness of amphibians.

The features of the structure of these cells in humans are more progressive. The double-concave shape, small size and lack of core significantly increase the amount of oxygen transported and the gas exchange rate. Human erythrocytes more efficiently perform respiratory function, quickly saturating all cells of the body with oxygen and freeing from carbon dioxide.